wc.rb

def diff(old, new)
  old.each_index{|idx|
    if old[idx].hash != new[idx].hash
      puts ">>> #{idx}: #{old[idx]}"
      puts "<<< #{idx}: #{new[idx]}"
    end
  }
  if old.length < new.length
      puts "<<< #{new.length - 1}: #{new.last}"
  end
  puts
end

def top_3_words(text)
  words = []
  top = {1 => 0}
  text.scan /\b(?:[[:alpha:]]|')+\b/i do |word|
    word.downcase!
    old = words.map(&:clone)
    if idx = words.find_index{|h|h[:word] == word}
      words[idx][:count] += 1
      if idx == 0
        top[words[idx][:count] - 1] += 1
        top[words[idx][:count]] = idx
      elsif words[idx - 1][:count] < words[idx][:count]
        np = top[words[idx][:count] - 1]
        words[idx], words[np] = words[np], words[idx]
        top[words[np][:count] - 1] += 1
        top[words[np][:count]] ||= np
      else
        top[words[idx][:count] - 1] += 1
        top[words[idx][:count]] = idx
      end
    else
      words.push(:word => word, :count => 1)
    end
  end
  words.first(3).map{|w|w[:word]}
end

p top_3_words("In a village of La Mancha, the name of which I have no desire to call to
mind, there lived not long since one of those gentlemen that keep a lance
in the lance-rack, an old buckler, a lean hack, and a greyhound for
coursing. An olla of rather more beef than mutton, a salad on most
nights, scraps on Saturdays, lentils on Fridays, and a pigeon or so extra
on Sundays, made away with three-quarters of his income.")